1. Field of the Invention
The present invention relates to a sense amplifier, and more particularly, to a self cut-off type sense amplifier for a static random access memory (SRAM) device.
2. Description of the Related Art
Generally, in an SRAM device, after a precharging operation is carried out, complementary data is read from a selected memory cell and is sensed by a sense amplifier. The power dissipation of SRAM devices is mainly determined by the precharging operation and the operation of the sense amplifier.
In order to reduce the power dissipation by the operation of the sense amplifier, self cut-off type sense amplifiers have been developed.
A prior art self cut-off type sense amplifier includes an amplifier circuit for amplifying a difference in potential between first and second data lines, an amplifier circuit activating circuit for receiving a sense start signal to activate the amplifier circuit and receiving a sense end signal to deactivate the amplifier circuit, a first sense detecting circuit for determining whether or not the amplifier circuit is activated in accordance with a first output voltage thereof and generating a first sense detection signal, a second sense detecting circuit for determining whether or not the amplifier circuit is activated in accordance with a second output voltage thereof and generating a second sense detection signal, and a sense end signal generating circuit for receiving at least one of the first and second sense detection signals and generating the sense end signal when a predetermined time has passed after at least one of the first and second sense detection signals is received. Thus, since the amplifier circuit is automatically deactivated after a read operation is completed, the power dissipation can be reduced. This will be explained later in detail.
In the above-mentioned prior art self cut-off sense amplifier, however, when a power supply voltage applied to the sense amplifier is reduced, the timing of deactivating the amplifier circuit is advanced, and at worst, the amplifier circuit is deactivated before output data is established. Also, this means that the power supply voltage of SRAM devices having such a self cut-off type sense amplifier is limited.